Stomping your foot angrily at ISPs and Internet facing entities to adopt a protocol noone cares and/or getting governments to intervene because you've exhausted all your options and progress is stagnant is not a transition plan, that's a hail mary.
If you can't enforce a flag day then that's all you're left with, isn't it? Other than maybe hacking into people's networks, upgrading them and then somehow preventing them from undoing your work.